At present, coal is still the main fuel in the power industry. With the social development and economic improvement, there is a sharp increase of demand of electric power, and a sharp decrease of coal storage, and also huge damage to our environment.
However, biomass is a renewable energy containing carbon. It is the characteristics of carbon neutral make biomass energy be applied for replacing part of fossil energy represented by coal, and reducing emission of carbon dioxide to mitigate greenhouse effect. Biomass and coal co-fired has been confirmed as an excellent method for biomass energy large-scale utilization by existing technology. It is an efficient and environmental method for producing energy, which can not only decrease the emission of pollution and carbon dioxide, but also utilize the biomass fuel with low heat value efficiently.
However, lacking of effective and reliable detection technology and device of biomass blending rate make it unable that the government formulate standards and policies for coal and biomass co-fired power generation subsidies, which limits the development of co-fired power generation technology and its market development in China.
Radiocarbon(14C) is a radioactive isotope of carbon, which was first discovered by Martin Kamen and Sam Ruben at the Radiation Laboratory of UC Berkeley in Feb. 27, 1940.
The cosmic rays hitting nitrogen atoms in the atmosphere make the 14C production. The living creatures' 14C radioactivity is consistent with the atmosphere level, because of the atmosphere carbon cycle. However, the coal's 14C radioactivity decays mostly, because of being buried deep in the ground for millions of years. So, the power station burn the biomass or not, and how much their burned, in other words, how is the blending ratio could be known by sampling the flue gas in the boiler flue of coal and biomass co-fired power station and measuring the 14C in the carbon dioxide.
The technique based on the radiometric dating of 14C isotopes was first applied for research of archaeology and geology, which is an effective method for biological component identification at present. Differ from the situation of garbage incineration power station, the supply of bio fuel is affected by season, which make the biomass blending rate is no more than 5% in the coal and biomass co-fired power station. While the biomass blending rate is low, accelerator mass spectrometry (AMS) is the most accurate detection method for 14C radioactivity, but the equipment is too expensive to be popularized.
In the prior art, there are also some methods to measure the 14C in the carbon dioxide by using scintillation counter. For example, the prior art attempts to obtain carbon dioxide by calcium carbonate suspensions or other absorbents, then count. However, under the condition of low blending ratio, the required detection accuracy can't be achieved.
When detected by liquid scintillation counters, enough carbon contents in sample of unit volume are required to reach certain accuracy, which only could be satisfied by benzene synthesis formerly. However, the process of benzene synthesis from carbon dioxide is very complex, and the problems of low conversion rate and long sampling preparation time exist.